1. Field of the Invention
The present invention relates to a heat-dissipating fan and, more particularly, to a heat-dissipating fan with a reduced axial height and with a reduced volume.
2. Description of the Related Art
Miniaturization is the trend of electronic products. Currently available heat-dissipating fans generally include a housing, a stator and an impeller. The stator includes a stator core, a coil unit, and a circuit board. The stator comprised of the stator core, the coil unit, and the circuit board limits reduction in the overall axial height of the heat-dissipating fans. As a result, it is difficult to achieve a light, compact design of the heat-dissipating fans and, thus, it is difficult to mount the heat-dissipating fans in miniature electronic devices or equipment.
Efforts have been made in reducing the axial height of the heat-dissipating fans by reducing the axial height and volume of the stator. However, the results are not satisfactory. FIG. 1 shows a conventional heat-dissipating fan 80 including a housing 81, a control unit 82, a stator 83, and an impeller 84. The housing 81 includes a fixed seat 811 and a shaft tube 812. The control unit 82 includes a control circuit board 821 mounted on a face of the fixed seat 811. The stator 83 is mounted around the shaft tube 812 and electrically connected to the control circuit board 821. The impeller 84 is rotatably mounted to the shaft tube 812. The axial height of the heat-dissipating fan 80 can be reduced by mounting the circuit board 821 of the control unit 82 on the face of the fixed seat 811. Such a heat-dissipating fan is disclosed in Taiwan Utility Model No. M291024. However, the drive circuit on the control circuit board 821 still has a certain height in the axial direction. Furthermore, the structure of the housing 81 is complicated, for the housing 81 must include the fixed seat 811 for mounting the control circuit board 821. Further, the stator 83 still includes a stator core and other components that prevent further reduction in the axial height. Overall, the effect in reduction of the axial height is limited.
FIGS. 2 and 3 show a conventional heat-dissipating fan 90 including a housing 91 having a compartment 911 in which a base 912 is formed. A circuit board 92 and a coil unit 93 are mounted on the base 912. A shaft tube 913 is formed on a center of the base 912. A rotor 94 is rotatably coupled to the shaft tube 913 and rotatably received in the compartment 911. By omitting components including a stator core, the axial height of the heat-dissipating fan 90 can be reduced. However, the drive circuit on the control circuit board 92 still has certain heights in the axial direction, causing limitation to further reduction in the overall axial height of the heat-dissipating fan 90 when the circuit board 92 is mounted on the base 912. Furthermore, the coil unit 93 protrudes beyond the face of the circuit board 92, such that the coil unit 93 and the circuit board 92 still have certain axial heights in the axial direction. As a result, it is difficult to achieve a light, compact design of the heat-dissipating fan 90 and, thus, it is difficult to mount the heat-dissipating fan 90 in miniature electronic devices or equipment.
Thus, a need exists for a heat-dissipating fan with a reduced axial height and with a reduced volume to meet the design trend of compactness and miniaturization.